Control system for dual temperature fluid delivery installations



G. E. ZIEGLER CONTROLSYSTEM FOR DUAIJ TEMPERATURE Aug; l5, 1967 FLUID DELI VERY INSTALLATI ON Filed Sept* 25, 1965 /NVuN'm/e. 660,265 E. Z /fGu-:e

United States Patent O 3,335,745 CONTROL SYSTEM FOR DUAL TEMPERATURE FLUID DELIVERY INSTALLATIONS George E. Ziegler, Evanston, Ill., assigner to Concrete Thermal Casings, Inc., Seattle, Wash., a corporation of Washington Filed Sept. 23, 1965, Ser. No. 489,589

Claims. (Cl. 137-375) The present invention relates to uid transporting pipe systems, particularly those which are encased in a thermal insulating embedment and usually buried underground.

In a pipe transporting system for supplying steam, there has always been the problem of moisture penetration with the result of an impairment of the insulating value of the embedment. In the past, attempts have been made to minimize the entry `of water into heat distributing systems through the use of an external casing to keep out the rwater, or by the use of waterproong mixtures added to the insulation to reduce the rate of migration of any water which might accidentally enter through the casings or come from breaks in the heat distribution pipe. In the case of steam transporting systems, there is an additional dii'liculty because during intervals of shutdown, there is a very substantial temperature drop occurring in the pipe. In a closed system, this results in a reduction in air pressure within the casing with the result that a partial vacuum is created in the pipe. Since there is unavoidably some leakage present in any substantial area of waterproof casing, eithermetallic or non-metallic, this partial vacuum tends to suck in water into the insulation. Then, when the heat is re-applied by introduction of steam or other heated fluid within the pipe, the vapor tends to leave the system through the pinholes which are unavoidably present in the insulation, but leaves only at a very slow rate. The net result is the accumulation of water within the insulation and all the harmful eiects which accompany water penetration.

Two commercially useful systems for overcoming these diculties have been described in Loper U.S. Patent No. 3,045,707 and in my previous U.S. Patent No. 3,045,708, both issued July 24, 1962. In accordance with the inven- Vtion set forth in the aforementioned patents, the embedment was provided with at least one vent passage formed within the connes of `the insulation and extending the full length of the insulation in parallel spaced relation to the pipe. The vent passage communicated with the ambient atmosphere, and means were provided for positively circulating air through the vent passage at a rate sutlicient to carry away moisture vapor which was forced into the vent passage by virtue of the thermal gradient existing between the periphery of the pipe and the outer periphery of the insulation. In the case of steam transporting systems, these vent passages were located at points Where the temperature of the insulation was about 170 to 210 F., in a typical installation.

fThe vented Huid transporting assemblies described in the aforementioned patents work very well where steam or hot water is being transported through the system. However, in modern installations, it is usually advisable to use the same pipe for transporting steam or hot water during the heating season, and cooling water for air conditioning purposes and the like during the cooling season. The pipe is located in an insulating embedment which is protected against exterior moisture penetration by the provision of a metallic or non-metallic moisture proong barrier at its periphery. However, with the use of the vented passages which correct the difficulties present during steam transmission, air is necessarily introduced into the embedment, thus at least partially defeating the Patented Aug. 15, 1967 ICC purpose of the barrier by inherently introducing some moisture vapor along with the air. In steam transmission, this additional amount of moisture is no problem because the thermal gradient existing between the pipe and the outer periphery of the embedment is suicient to drive 0H the moisture that may have been .introduced with the air passing through the vent passages. In the case of a cold Water transmission system, however, the cold pipe may cause condensation of this moisture vapor, thereby introducing Water into the insulation and impairing its insulating value.

One of the objects of the present invention is to provide an improved insulating system for pipes which carry fluids at widely varying temperatures periodically.

Another object of the invention is to provide an automatic means for communicating Vent passages in a thermal insulating embedment to the atmosphere when a relatively hot uid is passing through the pipe contained in the embedment, and for closing off or damping the 'vent passages when a colder iluid is being transported through the pipe.

Still another object of the invention is to provide a temperature responsive system for pipes which alternately carry heated and cooled fluids, to prevent the problems of moisture condensation existing when the pipe is carrying a cool fluid while still permitting venting of moisture vapor when a heated fluid is being transported.

Other objects and features of the present invention will become apparent to those skilled in the art from the following detailed description of the attached sheet of drawings which illustrate several embodiments of the invention.

In the drawings:

FIGURE 1 is a fragmentary view in elevation of the end of a typical embedment for fluid carrying pipes provided with vent passages, and embodying an automatic thermally responsive cont-rol system;

FIGURE 2 is an end elevational view, partly in crosssection, of the structure shown in FIGURE 1; and

FIGURE 3 is a view similar to FIGURE 2, but illustrating a modified form of the invention.

As shown in the drawings:

In FIGURE 1, reference numeral 10 indicates generally an embedment of the type used for insulating uid carrying pipes which are buried underground. The embedment 10 is disposed on a pad 11 composed of a poured structural concrete, resting upon the bottom of a trench dug for the purpose of accommodating the pipe line. A Huid carrying pipe 12 is surrounded by a thermal insulating embedment 13 composed of a lightweight insulating concrete, a compressed mass of aggregate particles coated with a thermoplastic film, a solidified resin foam, or other insulating embedment having good insulating properties. A typical lightweight thermally insulating concrete composition can be made with Portland cement and a lightweight aggregate, and including waterproofing agents such ascalcium stearate, powdered air floated pitch, or commercially available asphalt emulsions. A typical cornposition can be made by combining one bag of Portland cement weighing 94 pounds with 8 cubic feet of expanded vermiculite having a particle size of -10 to +65 mesh, 7 quarts of an asphalt emulsion prepared by mixing approximately 55 parts by weight of 50-60 penetration asphalt from California crude petroleum with about 43.35 parts of hot Water containing about 0.15 parts of caustic soda, and 26 gallons of water. The asphalt emulsion may be treated to convert the emulsion to the slow breaking mixing type by incorporating therein about 1.5 parts of a saponiiied Vinsol resin derived from the extraction of rosin with petroleum solvents.

The compressed, coated aggregate particles may be of the type described in GofLPatent No. 2,901,775. Typically, the composition may be expanded vermiculite coated with asphalt and compressed about the pipe until the volume of the particles is reduced by a value of from l to 25% of the original volume.

In the form of the invention shown, a pair of vent passages 14 and 16 is provided in the embedment in spaced parallel relation to the pipe 12 and running the full length of the embedment 13, all as described in the aforementioned Loper and Ziegler patents. The vent passages 14 and 16 communicate at their discharge ends to the ambient atmosphere by means of conduits 17 and 18 respectively.

The embedment 13 is confined within a water and moisture proof barrier which in the illustrated form of the invention takes the form of a membrane 19 composed of polyvinyl chloride resin or the like, two portions of such membrane being overlapped as indicated at numerals 21 and 22 and heat sealed or adhesively secured together to provide a waterproof and moisture proof barrier for the outer periphery of the embedment 13.

In accordance with the present invention, the conduits 17 and 18 are provided with valve means such as damper valves 23 and 24 respectively which are automatically positionable into an open or damping condition depending upon whether hot or cold fluid is passing through the pipe 12. The damper valves 23 and 24 are supported on shafts 26 and 27 respectively. The ends of the shafts 26 and 27 are connected to a pair of links 28 and 29 respectively, the two links being coupled together by a transversely extending rod 31. Centrally of the rod 31, the rod is engaged by a bifurcated end portion 32 of an actuator 33 which has its other end coupled to an expansible and contractible bellows 34 connected to the pipe 12: Expansion of the bellows 34 due to the heating of the pipe when steam is passing therethrough serves to move the actuator 33 in a direction such that the damper valves 23 and 24 are in their open position, thereby providing for free passage of the moisture laden air in the vent passages 14 and 16 to the ambient atmosphere. When the pipe 12 is carrying cooled lluid, however, the contraction of the bellows 34 serves to pivot the links 28 and 29 in the opposite direction, thereby positioning the dampening valves 23 and 24 in a location where they substantially reduce or close off the ow of air through the vent passages 14 and 16, effectively preventing the ingress of air into the system at a time when it is not desirable.

In the embodiment of the invention shown in FIGURE 3 of the drawings the mechanical structure of the ernbedrnent and the valve actuating means are the same as in the preceding gures, and so same reference numerals have been applied. In this form of the invention, however, there is illustrated a strictly electrical sensing system including an electrical sensing device 36 secured to the pipe 12, and serving to energize a solenoid 37 which in turn operates the actuator 33 to open and close the valves 23 and 24. The electrical sensing device 36 may be a bimetallic strip, a thermocouple, a temperature sensitive resistance element, or any electrical sensing device which operates on the basis of temperature diierences to energize or actuate a solenoid, a relay, or other actuator capable of moving the actuator bar 33. The operation of the device of FIGURE 3 is, of course, the same as that shown in FIGURES l and 2, that is, the electrical sensing element 36 detects wide variations in temperature of the pipe 12, to selectively open or close the damping valves 23 and 24, as required.

From the foregoing, it will be seen that the system of the present invention provides an automatic means for compensating for temperature differences in a Huid carrying pipe, and thereby control the actuation of valve means associated with the vent passages. By means of this system, the Vent passages are automatically opened when steam or heated fluid is passed Ithrough the pipe,

and closed when the passage of moisture laden air would be harmful to the system.

It should be evident that various modifications can be made to the described embodiments without departing from the scope of the present invention.

I claim as my invention:

1. In a fluid delivery system in which a pipe is embedded in a relatively porous insulating embedment and fluids of widely varying temperatures are passed through said pipe periodically, said embedment having at least one vent passage spaced from said pipe in generally parallel relation, the improvement which comprises thermally responsive means associated with said pipe, and valve means disposed in said vent and operated by said thermally responsive means, said thermally responsive means being operable to close off said vent passage when arelatively cold uid is passing through said pipe and to open said vent passage when a relatively hot uid is passing through said pipe.

2. The uid delivery system of claim 1 in which said embedment is enclosed by the moisture proofing barrier about its periphery.

3. The fluid delivery system of claim 1 in which said embedment consists of a lightweight thermal insulating concrete.

4. In a uid delivery system in which a pipe is embedded in a relatively porous insulating embedment and iluids of widely varying temperatures are passed through said pipe periodically, said embedment having at least one vent passage spaced from said pipe in generally parallel relation, the improvement which comprises a thermally expansible and contractible means connected to said pipe, damper means in said vent passage, and means interconnecting said expansible and contractible means with said damper means to damper said vent passage when a relatively cold uid is passing through said pipe and to open said vent passage when a relatively hot uid is passing through said pipe.

5. In a fluid delivery system in which a pipe is embedded in a relatively porous insulating embedment and uids of widely varying temperatures are passed through said pipe periodically, said embedment having at least one vent passage spaced from said pipe in generally parallel relation, the improvement which comprises a thermally responsive element positioned to respond to changes in temperature of said pipe, damper means in said vent passage, actuating means for moving said damper means from an open damping position, and a solenoid controlled by said thermally responsive element and coupled to said actuating means to open and damper said vent passage in relation to the temperature of said pipe.

6. The fluid delivery system of claim 5 in which said embedment is enclosed by a moisture proofing barrier about its periphery.

7. The fluid delivery system of claim 5 in which said embedments consists of a lightweight insulating concrete.

8. The fluid delivery system of claim 5 in which said thermally responsive element is a bimetallic element.

9. The fluid delivery system of claim 5 in which said thermally responsive element is a thermocouple.

10. The fluid delivery system of claim 5 in which said thermally responsive element is a temperature responsive electrical resistance.

References Cited UNITED STATES PATENTS 2,631,432 3/1953 Newcomb 137-468 X 2,662,547 12/1953 Comeau 137-468 2,675,020 4/ 1954 Breitwieser 137-468 3,045,708 7/ 1962 Ziegler 138-106 M. CARY NELSON, Primary Examiner. H. KLINKSIEK, Assistant Examiner. 

1. IN A FLUID DELIVERY SYSTEM IN WHICH A PIPE IS EMBEDDED IN A RELATIVELY POROUS INSULATING EMBEDMENT AND FLUIDS OF WIDELY VARYING TEMPERATURES ARE PASSED THROUGH SAID PIPE PERIODICALLY, SAID EMBEDMENT HAVING AT LEAST ONE VENT PASSAGE SPACED FROM SAID PIPE IN GENERALLY PARALLEL RELATION, THE IMPROVEMENT WHICH COMPRISES THERMALLY RESPONSIVE MEANS ASSOCIATED WITH SAID PIPE, AND VALVE MEANS DISPOSED IN SAID VENT AND OPERATED BY SAID THERMALLY RESPONSIVE MEANS, SAID THERMALLY RESPONSIVE MEANS BEING OPERABLE TO CLOSE OFF SAID VENT PASSAGE WHEN A RELATIVELY COLD FLUID IS PASSAGE THROUGH SAID PIPE AND TO OPEN SAID VENT PASSAGE WHEN A RELATIVELY HOT FLUID IS PASSING THROUGH SAID PIPE. 